Characterization of the Porosity Distribution within the Clinton Formation, Ashtabula County, Ohio
A combination of cores and geophysical logs were used to correlate the Clinton Formation across Ashtabula County and to help with an environmental analysis and porosity distribution. Reflectance, thin sections, porosity and permeability measurements, and geophysical logs helped to correlate sequences found within the Clinton Formation, along with reinforcing the known environmental interpretation of the Clinton Formation, and further regional information about the formation in Ashtabula County.
The Clinton Formation in NE Ohio is fine grain, semi- angular to semi-round, moderately sorted, quartz sandstone interbedded with shale. The sandstone contains silica cement, although calcite is found sparingly in the cement. Plugs were taken from core 908 at 13 locations within the core, producing 11 samples that were able to be measured for porosity and permeability. The porosity ranged from 4.2% to 9.2%, with an average of 6.0%. The permeability ranged from 0.0007 mD to 0.809 mD, averaging 0.128 mD. Reflectance and principle component analysis (PCA) were used to determine minor minerals throughout the formation. The red tinting on the sandstone is caused by goethite, and the green tint is caused by chlorite and amphibole. The PCA also produced a third component, correlating negatively with various clay minerals. This third component also highly correlates with the porosity measurements at the same depth, allowing interpretation of this component to be the siliciclastic porosity of the Clinton Formation. An equation from the linear trend of the porosity vs. component 2 was used to extrapolate porosity throughout the entire Clinton Formation core, giving a mean porosity of 6.02%, with ranges from 0.0% to 25.1%. The porosity distribution, along with the geophysical logs, were used to establish five sub-sections within the Clinton Formation that were correlated across one cross section line from East Ashtabula County to West Ashtabula County in the center of the county, indicating distribution of shale within the formation. Being able to identify shale and low porosity within the formation may help with further oil and gas exploration and enhanced oil recovery operations in the future.
AAPG Search and Discovery Article #90154©2012 AAPG Eastern Section Meeting, Cleveland, Ohio, 22-26 September 2012